Portable reciprocating power tool



Oct. 16, 1923.

J. J. ROBERTS PORTABLE RECIPROGATING POWER TOOL Filed Oct. 25 1920 ATTORNEY Patented Oct. 16, 1923.

- 1 UNIT-E11);snares- Pam-m; orrrcsf I v JOHN J. nosnizrs; or LOUISVILLE, KENTUCKYf PORTABLE RECIPROGATINGQPOWERL TOOL.

erationof the-nozzle and-(the chuck-for holding q thebits and =new;,-and useful means 1 of adj usting and: 5 controlling thc hammer end oii.ithe.. -shanks f of K saidfbits within the zone of l opjerationtof the plungers of isai'd recip- 2e rocating tools.

The objects of my invention are,- (1) to devise for; a: 1 portable reciprocating Tpower tool-new and useful-means for readily chang ing 'theastren-gthwand rapidity- 0f the ham amer strokes of? said tool at the-will of the operator I'during itsioperation; ,(2) to construct for the; nozzle 0t -ai-rpower, hammer-a mew adj nstable extension;- bit 1 chuoke'adapted. to holdLthe-bit-in alignment wit/lithe movement 3050f the hammer headpt said power ,tool and adapted to hold said-.bitnrigidly lILODB'POSL tioni-vwitlr relation-to .the'chuck; (3) I to providea for aa-powerhammer avnoveladjnstable extension-l chuck threadeditoserew longituditnallyinto @the'nozzleafi said hammer; and

- means.--,forrconfining the movement ofsaid:

extension chuck: iinwardi and outward lwithin certain predetermined: limits. 9 i)v to de sign for: a power hammer 1 new and useful 40 movable-bit chuclcfon holding the shank-of thebitin a position:tobepoundeclupon by the hammer head -as it fmovesmthrough its normal operative zone, novel means ionread- 11y moving ,said; chuck. a ndbit a I greater or 45. less distance iintossaid; operative zone to change-the strengtlnandrapidity of the hammen strokes and means forholding said sition in; said operative zones.

v pneumaticnhammers for. riveting, stonedrilling; stone-carving; Gulf, illustrated in the accompanying dr-awings whichform a'part .All 5 of Ithese objects are attained iin the presents invention and the improvements inr'ireciprocatingpower; to0l s,'E-electnic and of this specification, isfa practicable ap-v paratus embodying the aforesaid; novel extension chuck, operative; means and other new anduseful details of construction; arrangement. and combination of parts, all

'ofiwhich, together with rtheir functions will be 1 described in detailvwith' reference to said drawings, and will be definitely pointed out in the cla'ims-that follow the "description.

In said drawings, Figs-"land 2 are longitudinal sections in the plane AB of Fig 3, showing ,my threaded nozzle attached to the lower end of the casin'gof a powerhammer. In theseg Figures '1 and 2 also appear in their operative positions longitudinal sections :of '70 my extensionbit chuckftogether with"an elevation-of thecutting bit broken and a frag I ment; of the-hammer head of saidpower hammer. a

"Ill Fig. 1 may 1-beseen my new adj ustable -7 extension chuck screwed backdntothe nozzle as far ng. possible and holding the bitshank in -it-s innermost operative-position for the shortest and .7 most; I rapid strokes. 1 7 But E in Fig.2 may bersee'nhthese same parts Withmy B I new extension; chuck screwed outwardly as far 1 as possible andi' holding; the :bit-shank in its outermostposition for gettingthe longestpossible stroke from the hammer head :of said powertool'. V

FigJZ-S, is an'elevati'on of; [the bottom 0t my nozzle in first angle projection; witl1a-';part broken away to show controlling 7 detent in elevation and a'partial cross section of the nozzle, extension chuck and detentsslotxtherein, I

My invention has been-developed" forged eral use in electricand pneumatic hammers to whioh it maybe readilyattached orifitted. ith this-general purpose and specialobjects aforesaid in View I will now describe my invention ill-detail, pointingout-and explaining theusesandthe operations-of the various parts and combinations i thereofb throughout my inwention: as illustratedJn V the drawings hereinabove-specified,inwhich similar 'lettersandcharaeters refer tosimilar parts throughout theseveral iews- S p In Figs. 1 and 2,1 .is the threaded nojzzle that maybe: fitted tothecasing of 'anyrecip- 3 rocating-power tool in "some suitable way as by means 0i cap screws l3,' the-i edotted "line 2 representing therelati've position I of said casing. In Figs.l,-2-and'3, 1? indicates the base of said nozzle, 1 indicates the per foraway! In the inner threaded part of nozzle 1 tion forl delivering its full stroke upon the .head end of shank 4 in Fig. 2, in which the dotted l1ne 3 shows the positionof said tions in said base for the attaching cap screws 13, and 1,;the nozzle threads. 7

In Figs- 1 and 2, the numeral 3 indicates the hammer head of the reciprocating power tool drawn back to its extreme inner posihammer head in the delivery of'its full Fig. 3, andthe larger hexagonal portion 6 extending down into the'counterboring 14 as outlinedin Fig. 3, so that the shank shoulder 5 fits rigidly against the chuck shoulder 15 formed by the counterboring 14?, Figs. 1 and 2. In Fig; 3 nozzle threads 1 l and chuck threads 14 are shown only in out-s line. V

In Fig. 2 it should be observed'that the larger portion14 of the chuck '14, provided with chuck threads 14 has been screwed into its extreme outer position against the inner part of the nozzle 1. It can be readilyseen that when hit 6 is placed -.into;the tool for operation and chisel 7 is pressed against the I stone for cutting work; shank shoulder 5 will be pressed rigidly against "chuck shoulder 15 and the head end of shank 4 wills'tand in through tool casing 2 justfar enough to take the hlows of the plunging hammerhead 3 passing through its fullzone' of operation from 3 to 3', as seen in-Fig. 2, and delivering its longeststrokes; butfwhen the operator placeslhis fingers onichuck 14 at the'knurled ring 14 he can readily turn chuck 14 and'screw it along the threads1 *into nozzle 1. This inward movement of I chuck 14 allows bit .6 to sink back 1nto nozzle 1, and as the larger threaded portion 14 of chuck-14 advances toward the tool casing 2, shank-'4 advancesinwardly' toward hammer head 3 encroaching more and more into theoperativezone 3, 3 of hammerhead 3, and so shortens the hammerstrokeglving greater frequency of stroke per minute for the expenditure of a given amount of energy.

set the extension in place for a ce rtain o length of stroke and so to hold the shank 4 -111 I a position fixed for contmuouswork. This control of the movement trauma-.14 in my a longitudinal key slot 9, Figs. '1, 2 and 3, has been milled; and into the larger threaded portion 14 of the extension chuck 14 has been sunk a boring 12, into which has been fitted a helical compression spring 11 and a round-headed plunger 10 adapted to be pushed outwardly! by said spring, so that, while chuck '14 is being turned inthe nozzle '1, the round head of plunger 10 rides readily .over the nozzle threads 19-,until the key slot 9 is reached, into which plunger 10 forced by spring 11, jumps holding chuck14 from turning further until the operator again places his fingers upon the knurled ring 14 andv twists chuck-14 with' a torque suflicient to press the roundhead of plunger 10 with a side sweep out of-the slot 9, and then another rotation of the extension chuck can be made and the shank 4 set in any other position for a clifferent length stroke:

Fig. 1 shows the threaded portion 14 of my extensionchuck screwed back against the tool'casing 2 and the'shank- 4 at its ex-' treme inner position, giving us, consequently,

the shortest and the most rapid stroke of the hammer head 3-underthese conditions.-

Having thus described the features of 'my invention, the operation,construction, ar-

rangement and combination ofits parts,

what I 'claim'in my invention as new and useful and deslre to have outlined and speck efie'd in'Letters Patent; is set forth specifically in the following claims.

Claims; P

1. In a power hammen' the" combination of a" casing'fa' reciprocating-part within adapted toplunge in normal operation back 3 and forth a predetermined "distance, a nozzle attached to the hammer end of said'casing and provided with threaded axial boring, a deep longitudinalslot in one side of the threaded boring, and a tool chuck adapted with threads to screw longitudinally back and forth in said ,nozzle,sto lengthen or shorten the operative zone of saidrecipro eat ng part, an axial boring 1n 'sa1d tool chuck, a counterboring in thefouter end of said chuck, a bit provided with-shank andshoulder adapted to" fit 'slidably-into said chuck a predetermined distance, a'- spring pressed detent r'adially disposed fitted in the side ofsaid chuck and adapted in the screw ing ofsaid chuck inwardly or outwardlyin said nozzle to spring into said longitudinal slot and hold said chuck from rotating fur- "ther in normal operation, as described. 5 In the practical operation of the recip-' :rocatingpowertool it is often 'des'irablefto 2. In an electric or pneumatic reciprocatand forth over a. fixed-zone of operation', a

hollow cylindrical nozzle provided within ternal threads and *adaptedto be securely attache'd'to the endiio'f said tool casing, a

longitudinal slot, alongfthe inside-"of said nozzle, with an extension-v chuck provided with axial borings and with external threads adapted to fit the internal threads of said nozzle so that the chuck may be screwed in .wardly 0r outwardly along said nozzle, a

detent slidably fitted into the side of said chuck and adapted to engage the longitudicasing and a hammer head within adapted in normal service to move back and forth through a predetermined zone of operation, the combination of a bit havingja shank and a shank shoulder, a chuck for holding said bit and axial boring through said chuck for the shank to pass through, a counterboring in the outer end of saidchuck to admit the shank shoulder of said bit a predetermined distance, internal threads in said nozzle, external threads in said chuck adapted; to fit the nozzle threads, a longitudinal key slot through the nozzle threads, with a radial boring in the threaded side of said chuck, a round headed detent pin adapted to fit loosely in said radial boring, and a helical compression spring adapted to fit into the bottom of the radial-boring and to push continually against the said detentpin to cause the rounded head of said pin to plunge into said key slot at every revolution of said chuck to hold the chuck from further turnin under the stress of normal operation su stantially as described.

- 4. Ina reciprocating power tool having a Y casing and a hammer head'witliin adapted in normal operation to move back and forth through a predetermined range of stroke, an

extension chuck adapted-to hold a bit shank rigidly standing through said chuck a predetermined distance, a knurled ring on the outer end of said chuck for turning it, threads on the inner end of the chuck, a nozzle adapted to be attached to said casing and to hold said chuck, internal threads in said nozzle adapted to take the threads of said chuck so that the chuck carrying the bit shank in normal operative position to admit a long range of hammer stroke, as in Fig. 2, may be screwed in Wardly to any desirable position to admit a shorter hammer stroke, as in Fig. 1, and a key slot in said nozzle and a spring-pressed plunging detent in said chuck adapted to plunge into the slot at every revolution of the chuck to hold said bit 'shanksecurely in position to allow any desirable length of,

stroke, substantially as described.

In testimony whereof, I have hereunto set my signature in the presence of two witnesses.

' JOHN J. ROBERTS. Witnesses: r

'GEo. E. SCHUMAN, ALEXANDER C. SoHoMAN. 

